Various and sundry types of downhole fishing tools including overshots have been devised. Many of the devices known in the past have met with some commercial success. However, it is felt that they are lacking in that they do not provide an apparatus which is capable to grab and lift a fishing neck selectively with a quick release feature. Most downhole tools are equipped with a fishing neck for easy installation and retrieval The present invention is uniquely able to work with a fishing neck equipped item so that it can be either placed in the well or retrieved from the well. The present invention is operated by upward and downward reciprocal motion. This enables its use on a wireline where it is impossible to transmit rotational torque. If needed, this invention can be run on a tubing string but it finds its greatest application in the servicing of wells where a wireline is used. Wirelines are easier to use in servicing well because they require only a power source, wench and wireline. Tubing operated equipment normally requires a derrick and some type of rotary mechanism. It is much slower and much more expensive to use tubing operated tools.
The present invention thus finds an advantage over competitive tools. It is able to grasp and lift a fishing neck. If the fishing neck which is being lifted is first grasped and raised but resistance is encountered, the tool of this invention permits downward movement which releases the fishing neck. This avoids placing undue strain on the overshot, the cable and other equipment.
The overshot of this disclosure is a tool which is relatively simple to use. On a downward motion, the overshot is engaged with a fishing neck. After the fishing neck has been seized, a subsequent and similar downward motion reciprocates the scissor like grasping mechanism up above the fishing neck to release the grasp of the overshot. This is particularly advantageous.